Flow governing hydraulic system



March 21, 1961 R. D. RYNDERS ETAL 2,975,717

FLOW GOVERNING HYDRAULIC SYSTEM IN VEN TORS.

United States Patent FLOW GOVERNING HYDRAULIC SYSTEM 1 Robert D. Rynders and Edward 0. Brannon, Racine, Wis., assignors to Racine Hydraulics & Machinery, Inc., a corporation of Wisconsin Filed June 12, 1959, Ser. No. 819,907

1 Claim. (Cl. 103-120) This invention relates to a flow governing hydraulic system and moretparticularly to means for maintaining constant fluid flow in a hydraulic system having a hydraulic component such as a variable volume pump.

An object of the invention is to providea fiow feedback system for a hydraulic component such as the governor of a variable volume pump.

Another object of the invention is to provide a hydraulic system for governing fluid flow through a hydraulic component comprising, means for adjusting the component to obtain constant fluid flow, a differential pressure valve for controlling the component adjusting means, means for creating a pressure differential in a fluid line at the downstream side of the component, and means for subjecting said valve to the differential pressures in opposition whereby the valve takes a position dependent upon the pressures to control the component adjusting means.

A further object of the invention is to provide a system as defined in the preceding paragraph in which the pressure dilferential creating means comprises an orifice positioned in the fluid line at the downstream side of the hydraulic component.

Another object of the invention is to provide a vane type variable volume pump having a flow feed-back governor comprising, a rotor with slidable vanes, a rotor ring surrounding said vanes and positionable to control flow from the pump, a member engageable with the ring, a pressure differential valve for controlling the position of the member and ring, and means for applying differential pressures created in the pump outlet line to said valve for.controlling the member and ring positions.

Furtherobjects and advantages will become apparent 2,975,117 Patented Mar. 21, 1961 which the pump delivers a maximum volume of fluid. The rotor ring 6 is mounted within the cavity by engagement with a thrust block 7, a peripherally spaced governor piston 8 and a means for setting the full flow positioned at one side of the rotor 3. The intake port 16 communicates with the inner ends of the vanes 5 and functions to hydraulically balance the vanes. The intake port 17 communicates with the space between the rotor 3 and the rotor ring 6 to supply fluid to the space between the vanes.

Hydraulic fluid is discharged from the pump through the ports 19 and 20 in the port plate 18 which communicates with a chamber 21 in the casing connected to an outlet casing passage 22. From the foregoing it will be seen that the resultant force exerted on the rotor ring 6 during the pumping action is in a direction having a component urging the rotor ring against the governor piston 8 and thus the position of the governor piston 8 controls the position of the rotor ring 6. With the rotor ring 6 positioned as shown in the drawing, the pump is in a full flow condition with a rotor ring eccentric relative to the rotor 3. Movement of the rotor ring 6 toward the right as viewed in the figure to a position concentric with the rotor 3 would result in the pump being in a deadhead condition in which there is no fluid flow from the pump.

The hydraulic system embodies means for maintaining constant flow from the hydraulic component including means for obtaining a pressure differential in the fluid outlet line from the component and a pressure diflerential valve subjected to said differential pressures to be positioned thereby and have its position control the position of the governor piston 8 which controls the position of the rotor ring 6.

In order to have the differential pressure valve control the governor piston 8 a casing section 30 has a cylinder 31 to receive an enlarged section 32 of the piston 8. The cylinder 31 also houses a priming spring 33 for insuring proper action of the pump on start-up. The cyliufrom the following detailed description taken in connection with the accompanying drawing in which:

The figure is a vertical section taken through the center of the pump and associated components with parts broken away and with an external circuit shown diagramdisclosure is to be considered as exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

The scope of the invention will be pointed out in the amended claims.

A hydraulic component the flow from which is governed by the invention disclosed herein is disclosed in the drawing as a variable volume vane type pump. This comprises a casing 1 having an interior cavity 2 in which is disposed a rotor 3 mounted on a drive shaft 4 and carrying a plurality of vanes 5 movable inwardly and outwardly as determined by a rotor ring 6 disposed about the rotor 3. The rotor 6 is movable within the cavity 2 between a deadhead position in which the pump does not deliver any fluid and a full flow position in der communicates with a passage 34 formed in the casing section 30 whereby the cylinder may receive pressure fluid to thus urge the piston 8 toward the rotor ring 6 or the cylinder may be connected to drain with the result that only the priming spring 33 urges the piston 8 towards the left with a lesser force.

The pump outlet passage 22. connects with a line 35 leading to a fluid operated device (not shown). The line 35 has means for setting up a pressure differential therein, namely, a flow restricting orifice 36. A branch line 37 connected to the line 35 at the upstream side of the orifice 36 leads to-a passage 38 formed in the casing section 30 while a second branch line 39connected into the line 35 at the downstream side of the orifice 36 leads to a passage 40 formed in a block 41. A branch line -42 leads from the upstream side of the orifice 36 to a passage 43 formed in a valve block 44.

The orifice 36 functions to create a pressure differential in the line 35, when fluid flow occurs between the upstream and downstream sides of the orifice and the line 37 functions to pick off the pressure at the upstream side of the orifice 36 while the line 39 picks off the pressure at the downstream side of the orifice.

The pressure differential valve embodies a piston type valve member 50 which is urged toward the left, as viewed in the figure, by a spring 51 which is adjustable by means of a threaded shaft 52 extending outwardly of the block 41 and threadably attached thereto. The valve member 50 is movably mounted within a sleeve 53 which is in fluid communication at opposite ends thereof with the fluid line 35 at the upstream and downstream sides of the orifice 36 through the lines 37 and 39, respectively. A passage 38 connecting with the line 37 communicates with the left hand end of the sleeve 53 interior to direct fluid pressure against the left-hand face of the valve member 50 to oppose the force of the spring 51. Fluid from the downstream side of the orifice 36 enters the passage 40 which communicates with a passage 55 extending transversely into communication with the interior of the sleeve 53 at the right hand thereof. Thus fluid pressure is directed against the right hand end of the valve member 50 and urges the valve member in the same direction as the spring 51. v

The sleeve 53 has three laterally spaced passages 56, 57 and 58 with communication therebetween being controlled by the valve member 50 having a land 59 intermediate the ends thereof. The passage 56 communicates with the passage 40 and 43 connected to the fluid line 39 while the sleeve passage 57 communicates with a passage 60 formed in the valve block 44 which communicates with the transverse passage 34 leading to the governor cylinder 31. The sleeve passage 58 communicates with a passage 61 formed in the valve block 44 which is connected to a line 62 leading to the tank.

With the pump components positioned as shown in the figure, the forces controlling the pump displacement are in balance, i.e., the pressure differential across the orifice 36 is in fluid communication with the valve 50. The higher of the two pressures, or the upstream pressure is sensed at the valve 50 through line 37 and 38 causing an unbalance of forces tending to move the valve 50 to the right. The spring 51 supplies the force necessary to prevent this movement at one predetermined pressure differential. Any change in flow across orifice 36 due to pump slippage or changes in the pump speed due to various loads applied to the unit, is sensed at the orifice 36 as a change in the pressure differential. Since the spring 51 force is constant the pressure differential, or the forces acting at the opposite ends of valve 50, will cause it to respond to any disturbance caused by a change in flow at orifice 36.

An increase in flow due to an increase in pump speed or unloading of the unit will cause the valve 50 to be moved to the right, allowing some oil in chamber 31 to flow to tank through line 34. This allows the ring to drift or move toward the deadhead position enough to satisfy the flow requirements needed to re-establish the pressure differential dictated by the spring 51. Assuming the parts of the pump are near the deadhead position, a decrease in flow in the line 35 will cause the valve 50 to move to the left. This connects the 4 governor cylinder 31 with pressure fluid through the sleeve passages 56 and 57 which shifts the governor piston 8 toward the left, as viewed in the figure, to move the rotor ring 6 in a direction toward the full flow position.

Pressure protection is built into the system by having a relief valve embodying a ball valve member spring urged by a spring 71 to a position to close a passage 72 communicating with the right hand interior of the sleeve 53 and when openable connecting the said space with a lateral passage 73 leading to the tank.

The foregoing detailed description is given for clearness of understanding only and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

We claim:

A variable volume vane type pump with a unitary flow feed-back governor comprising, a casing with a cavity, a rotor with slidable vanes in said cavity, a movable rotor ring surrounding said rotor and shiftable to control the pump delivery volume, a governor for controlling the position of the ring including a casing component having a cylinder, a piston slidable'in said cylinder and operatively engaged with the ring and a spring urging said piston toward the ring and the ring toward a full flow position, governor controlling means affixed to said casing including a pressure differential valve with a valve member for controlling flow of presssure fluid to said governor cylinder to act in the same direction as the spring, a sleeve movably receiving the differential valve member, a spring nested within the valve member urging the valve member to a position to connect the governor cylinder with pressure fluid to shift the pump ring toward full flow, and said valve member controls the connection of the governor cylinder to either pressure fluid or drain, means for creating differential pressures in a pump outlet line, means for applying said differential pressures to said valve, and a pressure relief valve in said casing for limiting the pressure acting on the valve member.

References Cited in the file of this patent UNITED STATES PATENTS 2,238,061 Kendrick Apr. 15, 1941 2,600,632 French June 17, 1952 2,600,633 French June 17, 1952 2,698,579 Hammond Jan. 4, 1955 2,716,946 Hardy Sept. 6, 1955 2,724,335 Eames Nov. 22, 1955 2,742,862 Banker Apr. 24, 1956 2,768,582 Klessig et al Oct. 30, 1956 2,768,585 Hardy Oct. 30, 1956 2,845,876 Keel Aug. 5, 1958 2,894,458 Hallman July 14, 1959 FOREIGN PATENTS 625,405 Germany Feb. 8, 1936 

